In an electric compressor incorporating an electric motor for driving a compression mechanism, particularly, an electric compressor used for a refrigeration system for vehicles, etc., because usually a high-voltage motor is used, a structure is required from the viewpoint of safety and the like, wherein there is no fear of leak by insulating between a terminal portion of a motor and its joint, and a motor housing portion and a compressor housing portion (that is, a body portion). In such an electric compressor, usually, a structure is frequently employed, wherein a joint between an external terminal for supplying power to the incorporated electric motor and an end of a wire from a stator of the electric motor is provided, and the joint is contained in the compressor housing, in particular, in a hollow projected portion extending outward.
Further, even in an electric compressor using a high-voltage motor and used for a refrigeration system for vehicles and the like, the above-described joint is frequently designed similarly in a general compressor for domestic electric equipment. Namely, a terminal joint is held only by a force of a spring attached to a terminal, and in most cases, special countermeasures for vibration proof are not employed. For example, in most cases, terminal and coupler for general compressor for domestic electric equipment are used, a structure pressing a terminal joint only by a spring force is employed, and it is not fixed by suing a fixing means such as a bolt. Therefore, when a large load greater than the spring force is applied, there is a possibility that causes disconnection or instantaneous interruption (a phenomenon causing an instantaneous separation and breaking an electric connection instantaneously) of the terminal joint. In particular, in an electric compressor mounted on a vehicle which is likely to be applied with an external force due to vibration, such a problem is liable to occur. In such a structure, however, productivity and cost are good because the structure is simple.
On the other hand, as a structure for enhancing the vibration proof performance of the motor terminal joint, for example, as depicted in FIG. 4, also known is a structure wherein an epoxy resin 103 is injected around the terminal joint between external terminal 101 for supplying power and end of wire 102 from a stator, thereby molding the portion around the joint. The resin 103 insulates between compressor housing 104 and the terminal. In this structure, since the portion around the terminal is molded by the resin, although the possibility of disconnection due to vibration becomes less, because the metal forming the terminal and the resin cured after injected are different in coefficient of linear expansion from each other, there is a possibility that it is deformed in a direction cutting the terminal depending upon the temperature therearound. Further, although the cost is low because the structure is simple, the productivity is poor because a time for curing the resin on a production line is required.
Such a problem with respect to the joint exists not only in a simple electric compressor incorporating an electric motor for driving a compression mechanism but also in a hybrid compressor using an incorporated electric motor and an external drive source different from the incorporated electric motor (for example, an engine for running a vehicle) as drive forces for respective compression mechanisms.
For example, as a hybrid compressor used in a refrigeration system for a vehicle, proposed is a hybrid compressor in which a scroll type first compression mechanism driven only by a prime mover for a vehicle and a scroll type second compression mechanism driven only by an incorporated electric motor are integrally assembled at a condition where fixed scrolls of both compression mechanisms are disposed back to back (Patent document 1). By such a hybrid compressor, it becomes possible to operate the respective compression mechanisms individually or simultaneously and achieve an optimum discharge performance depending upon requirements at a time to be controlled. Even in such a hybrid compressor, there is the above-described problem in the terminal joint for the incorporated electric motor. Patent document 1: JP-A-2003-161257